Datasheet

336
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
Notes: 1. Z0: should be zero for all SPM commands, byte select for the (E)LPM instruction.
2. See “Addressing the Flash During Self-Programming” on page 328 for details about
the use of Z-pointer during Self-Programming.
ATmega1280/1281 Boot
Loader Parameters
In Table 143 through Table 144, the parameters used in the description of the Self-Pro-
gramming are given.
Note: 1. The different BOOTSZ Fuse configurations are shown in Figure 136.
PAGEMSB 6 Most significant bit which is used to
address the words within one page (128
words in a page requires seven bits PC
[6:0]).
ZPCMSB Z15 Bit in Z-pointer that is mapped to PCMSB.
Because Z0 is not used, the ZPCMSB
equals PCMSB + 1.
ZPAGEMS
B
Z7 Bit in Z-pointer that is mapped to PCMSB.
Because Z0 is not used, the ZPAGEMSB
equals PAGEMSB + 1.
PCPAGE PC[14:7] Z15:Z8 Program Counter page address: Page
select, for Page Erase and Page Write
PCWORD PC[6:0] Z7:Z1 Program Counter word address: Word
select, for filling temporary buffer (must be
zero during Page Write operation)
Table 142. Explanation of different variables used in Figure 137 and the mapping to the
Z-pointer, ATmega640
Variable
Corresponding
Z-value
(2)
Description
(1)
Table 143. Boot Size Configuration, ATmega1280/1281
(1)
BOOTSZ1 BOOTSZ0 Boot Size Pages Appli-cation Flash Section Boot Loader Flash Section End Application Section Boot Reset Address (Start Boot Loader Section)
11
512
words
4
0x0000 -
0xFDFF
0xFE00 -
0xFFFF
0xFDFF 0xFE00
10
1024
words
8
0x0000 -
0xFBFF
0xFC00 -
0xFFFF
0xFBFF 0xFC00
01
2048
words
16
0x0000 -
0xF7FF
0xF800 -
0xFFFF
0xF7FF 0xF800
00
4096
words
32
0x0000 -
0xEFFF
0xF000 -
0xFFFF
0xEFFF 0xF000